Contents of /eclass/elisp-common.eclass

Partial sync from Emacs overlay.
elisp.class:
In the "simple elisp" case, explicitly assign S=${WORKDIR} in
elisp_src_unpack.
elisp-common.eclass:
Remove function elisp-comp; it is not used by anything in the tree.
Reindent documentation to 72 columns for better readability.